In the related art, a driving supporting system is known which prevents a head-on collision. For example, in a system described in Patent Literature 1, when there are a priority vehicle which is traveling on a priority road and a nonpriority vehicle which is traveling on a nonpriority road which crosses the priority road, information regarding the nonpriority vehicle which is driven hazardously is notified through vehicle-to-vehicle communication from the nonpriority vehicle to the priority vehicle.    [Patent Literature 1] Japanese Unexamined Patent Application Publication No. 2007-323184